Why cockroaches in Shenzhen are so fat! And there are variants?

Shenzhen is located in the subtropical zone, with hot and humid air, which adapts to the growth environment of cockroaches. As for mutation, it is because Shenzhen is an industrial city, most garbage contains a lot of chemical elements, and most foods in our lives also contain a lot of hormones, so cockroaches will mutate after eating them, just like the city where we live, and many kinds of influenza often occur.